As is known, the problem of conferring high fire resistance to polymers, in particular to polymeric filaments, fibers or films, is of great present importance, in particular in the textile arts, and the requirements of low inflammability and self-extinguishing properties--which together may be referred to as "fire resistance" characteristics--have become increasingly severe, also in view of legislative developments in various countries. The methods widely adopted involve the introduction into the polymer of fire resistance agents or the introduction into the molecule of the polymers of fire-resistant groups. Said agents and groups often contain a halogen as the basic element. Such methods however have numerous drawbacks, and in particular not only do they involve modifications of the manufacturing processes and a substantially higher cost of the finished products, but they also confer to the polymer the harmful property of evolving poisonous or at least dangerous fumes to the extent that there is a tendency in the legislation of many countries drastically to limit the amount of halogens which may be present in any closed room.